Electrode for electron discharge devices



April 7, 1936- P. KNIEP'EN ELECTRODE FOR ELECTRON DISCHARGE DEVICES Filed May 1e, 1954 Patented Apr. 7, 1936 UNI-TED STATES PATENT OFFICE ELECTRODE FOR ELECTRON DISCHARGE DEVICES Germany Application May 16, 1934, Serial No. '725,844 In Germany May 19, 1933 4 Claims.

AMy invention relates to electrodes for electron discharge devices, more particularly to improvements in electrodes made of thin Sheet material.

Itisat times desirable to provide electron disi" charge devices with electrodes having Walls preferably between 2 to 3 mils in thickness and of large area. Electrodes of this sort combine reduced mass with large radiating powers so that, even when carrying a comparatively large load,

m they will not become unduly hot. Reduced mass or volume moreover facilitates mounting and the electrodes are cheaper to manufacture. This is especially true of the anodes of large-load or large-power rectifiers, transmitter tubes and la amplifier tubes. However, thin-Walled electrodes of the kind here considered have little strength or rigidity, so that there is an ever-present danger of their being bent or deformed when being built into a tube, or of their altering their form during operation of the tube. It may also happen that as a result of electrostatic forces or due to percussions or vibrations of a mechanical nature, they may change their shape and thus make contact with other electrodes rendering the tube 25 inoperative.

The reinforcement of the electrodes by stayingl Ior supporting sheet strips mounted perpendicularly upon the electrode surface is not feasible under all conditions, and in addition such an arrangement would be hard to make. A certain amount of reinforcement or stiffening of the electrodes is attainable by ribor fin-shaped bulges pressed in the material. Such ns or ribs are usually either rectilinear or curvilinear (annular), about one-third of a millimeter wide and from one-half to one millimeter deep. In the reinforced form of electrode described the intervals between these ns or ribs are large in comparison to the width of the ribs, and as a result the number of ns upon the electrode is not large so that the amount of stiffening obtainable is entirely inadequate in most instances.

The object of the present invention is to pro- 45 vide an electrode having a thin wall but which nevertheless has suicient rigidity and strength to prevent deformation during assembly and While in use without resorting to special reinforcing and supporting devices.

50 In accordance with my invention, the desired strength and rigidity is obtained by providing the surface of the electrode with a large number of alternating projections and recesses, preferably conical, and preferably perforated at the tips,

55 the distance between the centers of the projec- (Cl. Z50-27.5)

tions and recesses being from 0.5 to 2 millimeters with the result that the projections and the recesses are substantially contiguous. The manufacture of the protruded sheet metal for electrodes is effected, for example, by means of a press or 5 cooperating rollers between which the thin sheet metal is fed.

By forming the thin sheet metal as described, the strength of the sheet is substantially increased because the portions of the electrode sheet forming the projections and recesses act to stiffen the sheet. By cold working the sheet material into the form described a change in the crystal structure seems to result with an additional gain in strength of the sheet due to this change. The working or pressing, if desired, could be effected at the same time as the cutting or bending of the electrode from the thin sheet material.

An electrode made in accordance with my invention has increased strength and its enlarged area increases its heat radiating properties. An electrode of the kind described is particularly suitable for supporting coatings of the sort employed for increasing the heat radiating qualities of the electrode, since such coatings will adhere to the electrode with greater tenacity. An electrode of this type also facilitates the removal of occluded gases from the electrode.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which-Figure 1 is a side elevation of an electrode mount having an anode made in accordance with my invention; Figure 2 is an enlarged partial cross section of the anode taken along the line 2-2 of Figure l; Figure 3 shows an electrode mount hav- 40 ing a screen grid made in accordance with my invention.

In Figure 1, the press l supports a tubular anode 2, grid 3 and cathode 4. According to my invention, the active electrode surface of anode 2 is provided with adjacent funnel-shaped or conical elevations and depressions 5 and 6 which are shown in greater detail in Figure 2 drawn to an enlarged scale.

As can be seen from this cross section, the contours of the projections and recesses are continuations of each other so that very little of the formed sheet lies in the plane of the sheet. These projections and depressions not only increase the rigidity of the material but act as radiating ns.

In Figure 3 the mount is provided with an inner screen 'I which supports a top shield 8 to the rim of which is fastened the tubular outer vscreen electrode 9 made in accordance with my invention. 'Ihis shield permits easy heating of the electrodes during exhaust and facilitates radiation of the heat from the electrodes Within the screen during operation.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is,-

1. A tubular electrode for an electron discharge device and comprising a thin sheet material of from 2 to 3 mils thick having a surface provided with a large number ofy contiguous perforated cone-shaped projections and recesses for rendering said electrode strong and rigid.

2. A tubular electrode for electron discharge devices and comprising a thin sheet material of from 2 to 3 mils thick having a surface provided with a large number of contiguous cone-shaped projections and recesses for rendering said electrode strong and rigid, said projections and recesses being perforated at their tips.

3. A tubular electrode for an electron discharge device comprising thin sheet metal from 2 to 3 mils thick having contiguous cone-shaped projections and recesses perforated at their tips with their centers spaced from .5 to 2 millimeters apart.

4. A screen grid tube having an electrode mount comprising a concentric cathode, grid and anode,

an inside screen grid positioned between said grid and anode, a top shield connected to said inner screen grid and an outside screen electrode concentric with said cathode, grid and anode and secured to therrim of said top shield and comprising sheet metal from 2 to 3 mils in thickness having contiguous cone-shaped projections and recesses perforated at their tips With the distance between the centers of said projections and recesses from .5 to 2 millimeters.

PETER KNIEPEN. 

